The invention relates generally to diodes and, more particularly, to a microwave diode adapted for use in switched microwave termination circuits.
As is known in the art many microwave devices require that a given port be switched to a matched load. This provides a matched condition for the port when in an isolation state that would otherwise be highly reflective. In the prior art a common technique used to provide such matched load is to have a series diode at the port serially coupled to a termination resistor. This circuit requires the use of individual components including a series diode, termination resistor and a ground strap to interconnect the diode and the resistor along with appropriate thermal compression bonding and/or soldering steps.
Another prior art technique involves the use of a diode connected between the port and ground with the diode driven into the forward bias state by a small current. The amount of current is adjusted such that the diode has a proper resistance value to provide a matched load. With such technique, however, the control of the small current is difficult. Additionally, the current required to provide the proper resistance value may vary from diode to diode making it necessary to customize each device. Still further, a diode partially forward biased is quite temperature sensitive and, consequently, the device may not be properly terminated over a wide range of temperature.